One common type of machine for blow molding hollow articles is known as an injection blow molding machine wherein a core rod is inserted successively into an injection mold to form a preform or parison and is thereafter used to transfer the parison to a blow mold where the parison is blown outwardly against the confines of the mold to form hollow plastic article such as a container.
In one type of injection blow molding machine, a turret has a plurality of circumferentially spaced surfaces, for example, three surfaces, each of which supports a plurality of spaced core rods. When the turret is rotated, the core rods are moved successively first to a preform or injection station having an array of preform or parison molds, then to a blow molding station having an array of blow molds where the parisons are blown to form the hollow articles, and finally to an unload station where the hollow articles are removed from the core rods permitting a new cycle to begin.
In various blow molding machines, it has heretofore been suggested that labels be positioned in the hollow blow molds before blowing the hollow article so that the final article has a label applied to the exterior surface thereof. Insofar as is known, in-mold labeling in injection blow molding machines has not been achieved.
Accordingly, among the objectives of the present invention are to provide a method and apparatus for in-mold labeling in an injection blow molding machine wherein the in-mold labeling can be achieved without reducing the normal operating cycle and wherein the labels can be accurately positioned both longitudinally and circumferentially with respect to the parting line of the blow molds.
In accordance with the invention, a positioning apparatus positions a plurality of labels at the blow station adjacent each of the blow molds and a plurality of cylindrical vacuum mandrels rotate to pick-up the labels and are then translated to transfer the labels into the open bottoms of the molds. The mandrels are then retracted and the bottom plates of the molds are closed and the hollow articles are blown outwardly by expanding the parisons resulting in the hollow articles with the labels on the exterior surfaces thereof.